1. Field of the Invention
The present invention relates generally to the field of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.) and, in particular to a new and useful method and apparatus for reducing and/or eliminating various liquid discharges from one or more emission control equipment devices (e.g., one or more wet flue gas desulfurization (WFGD) units). In another embodiment, the method and apparatus of the present invention is designed to reduce and/or eliminate the amount of liquid waste that is discharged from a WFGD unit by subjecting the WFGD liquid waste to one or more drying processes, one or more spray dryer (or spray dry) absorber processes, and/or one or more spray dryer (or spray dry) evaporation processes. In still another embodiment, the method and apparatus of the present invention permits: (a) control of the chemistry, physical properties and/or the composition of the liquid material discharged from a WFGD unit; and/or (b) control of one or more downstream air quality control systems (AQCS) by injection of the remaining liquid material from one or more drying processes and/or devices, one or more spray dryer (or spray dry) absorber processes and/or devices, and/or one or more spray dryer (or spray dry) evaporation processes and/or devices.
2. Description of the Related Art
As is known by those of skill in the art, various processes and/or apparatuses are utilized in connection with boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, waste incinerators, processing plants, etc.) to treat the combustion and/or flue gases generated therefrom. Some of these air quality control systems (AQCS) include various processes and/or apparatuses that achieve the control, reduction and/or mitigation of various compounds including, but not limited to, SOx, NOx and solid particulate prior to their emission into the atmosphere.
One of the most widely utilized emission control technologies is the use of one or more wet flue gas desulfurization (WFGD) units to control SOx emissions. WFGD units and the process of utilizing such units are well known to those of skill in the art as discussed in Steam/its generation and use, 41st Edition, Kitto and Stultz, Eds., Copyright 2005, The Babcock & Wilcox Company, Barberton, Ohio, U.S.A., particularly Chapter 35—Sulfur Dioxide Control, the complete text of this book is hereby incorporated by reference as though fully set forth herein.
These various sulfur dioxide control processes, especially those based on WFGD technologies, inevitably generate a stream of liquid waste necessary to keep their chemical-physical parameters under control and, therefore, ensure their correct functioning. This so produced liquid waste is traditionally treated in dedicated plants (or sub-plants) to ensure compliance with various liquid discharge regulations so that such liquid discharge can be further discharged into, for example, surface waters. Among other goals sought to be accomplished by these liquid treatment plants is the reduction of one or more compounds including, but not limited to, mercury compounds, selenium compounds, cadmium compounds, etc.
In order to control, reduce, and/or eliminate the discharge of the liquid waste from one or more WFGD units into surface waters various systems have been suggested in the prior art. However, such systems suffer from various drawbacks including, but not limited to: (i) the inability to process liquid waste, or a liquid waste stream, from a wide range of sources (e.g., any type of blow-down water, any type of make-up water and/or any type of make-up water treatment byproduct, any liquid waste from any WFGD unit or other AQCS unit, coal pile run-off and/or effluent, and/or ash pond run-off and/or effluent, etc.); and/or (ii) a difficulty in processing liquid waste, or a liquid waste stream, from an absorber recirculation tank (ART) (also referred to as an absorber reaction tank (ART)—hereinafter just referred to as an absorber recirculation tank (ART) for purely convenience sake) of one or more WFGD units with a total suspended solids content above about 1 percent by weight, or even above about 5 percent by weight.
Given the above, a need exists for a method and/or apparatus (or system) that provides for the reduction, mitigation and/or elimination of any liquid waste, or liquid waste stream, from any of a wide range of sources including, but not limited to, those generated by various AQCS devices (e.g., a WFGD).